Corrected a crash condition that can occur if a GDS file pointed

to by GDS_FILE does not exist.

VERSION

@@ -1 +1 @@
-8.3.90
+8.3.91

calma/CalmaWrite.c

@@ -826,7 +826,8 @@ calmaProcessDef(def, outf, do_library)
 	    /* This is a rare error, but if the subcell is inside	*/
 	    /* another vendor GDS, it would not normally be output.	*/
 
-	    DBPropGet(def->cd_parents->cu_parent, "GDS_FILE", &isReadOnly);
+	    DBPropGet((def->cd_parents->cu_parent == NULL) ? def :
+			def->cd_parents->cu_parent, "GDS_FILE", &isReadOnly);
 	    if (!isReadOnly || isAbstract)
 		TxError("Calma output error:  Can't find GDS file \"%s\" "
 				"for vendor cell \"%s\".  Using magic's "